A fashion war has broken out in Spanish politics. Industry minister Miguel Sebastián attended parliament this week without a tie.

Parliamentary speaker José Bono of the ruling Socialist camp took offence and sent Sebastián a gift: a tie, with a note that read: "I hope you like it."

Sebastián declined to wear the tie and the next day responded with a present for Bono: a digital thermometer.

It was Sebastián's way of saying the air conditioning was too fierce at the congress of deputies, despite a 2007 ruling to keep government buildings warmer in summer to save energy.

It is not mandatory to wear a tie in parliament, and some opposition politicians do not, but the Spanish media says this was the first time a male government minister showed up for a debate without wearing one.

Bono tried to downplay the exchange, but by then it was too late. Socialist party spokesman José Blanco said it was silly to try to force government ministers into "uniforms" with ties.

Labour and immigration minister Celestino Corbacho met French officials at the foreign ministry, then walked outside, took off his tie and unbuttoned his top button.

"One can be formal with and without a tie," Corbacho said.

Even the opposition got into the debate. Iñaki Anasagasti of the Basque Nationalist party said Sebastián was out of line and trying to divert attention from Spain's real problems. "The time to go without a tie is on weekends," he said.